GASPS-A Herschel Survey of Gas and Dust in Protoplanetary Disks: Summary and Initial Statistics
Artikel i vetenskaplig tidskrift, 2013

We describe a large-scale far-infrared line and continuum survey of protoplanetary disk through to young debris disk systems carried out using the ACS instrument on the Herschel Space Observatory. This Open Time Key program, known as GASPS (Gas Survey of Protoplanetary Systems), targeted similar to 250 young stars in narrow wavelength regions covering the [OI] fine structure line at 63 mu m the brightest far-infrared line in such objects. A subset of the brightest targets were also surveyed in [OI]145 mu m, [CII] at 157 mu m, as well as several transitions of H2O and high-excitation CO lines at selected wavelengths between 78 and 180 mu m. Additionally, GASPS included continuum photometry at 70, 100 and 160 mu m, around the peak of the dust emission. The targets were SED Class II-III T Tauri stars and debris disks from seven nearby young associations, along with a comparable sample of isolated Herbig AeBe stars. The aim was to study the global gas and dust content in a wide sample of circumstellar disks, combining the results with models in a systematic way. In this overview paper we review the scientific aims, target selection and observing strategy of the program. We summarise some of the initial results, showing line identifications, listing the detections, and giving a first statistical study of line detectability. The [OI] line at 63 mu m was the brightest line seen in almost all objects, by a factor of similar to 10. Overall [OI]63 mu m detection rates were 49%, with 100% of HAeBe stars and 43% of T Tauri stars detected. A comparison with published disk dust masses (derived mainly from sub-mm continuum, assuming standard values of the mm mass opacity) shows a dust mass threshold for [OI] 63 mu m detection of similar to 10(-5) M-circle dot. Normalising to a distance of 140 pc, 84% of objects with dust masses >= 10(-5) M-circle dot can be detected in this line in the present survey; 32% of those of mass 10(-6)-10(-5) M-circle dot, and only a very small number of unusual objects with lower masses can be detected. This is consistent with models with a moderate UV excess and disk flaring. For a given disk mass, [OI] detectability is lower for M stars compared with earlier spectral types. Both the continuum and line emission was, in most systems, spatially and spectrally unresolved and centred on the star, suggesting that emission in most cases was from the disk. Approximately 10 objects showed resolved emission, most likely from outflows. In the GASPS sample, [OI] detection rates in T Tauri associations in the 0.3-4 Myr age range were similar to 50%. For each association in the 5-20 Myr age range, similar to 2 stars remain detectable in [OI]63 mu m, and no systems were detected in associations with age >20 Myr. Comparing with the total number of young stars in each association, and assuming a ISM-like gas/dust ratio, this indicates that similar to 18% of stars retain a gas-rich disk of total mass similar to 1 M-Jupiter for 1-4 Myr, 1-7% keep such disks for 5-10 Myr, but none are detected beyond 10-20 Myr. The brightest [OI] objects from GASPS were also observed in [OI]145 mu m, [CII]157 mu m and CO J = 18 - 17, with detection rates of 20-40%. Detection of the [CII] line was not correlated with disk mass, suggesting it arises more commonly from a compact remnant envelope.

Författare

W. R. F. Dent

Atacama Large Millimeter-submillimeter Array (ALMA)

W. F. Thi

Rijksuniversiteit Groningen

Verimag

I. Kamp

Rijksuniversiteit Groningen

J. P. Williams

University of Hawaii at Manoa

F. Menard

Verimag

S. Andrews

Harvard-Smithsonian Center for Astrophysics

D. R. Ardila

National Aeronautics and Space Administration

G. Aresu

Rijksuniversiteit Groningen

J. C. Augereau

Verimag

D. Barrado

Centro Astronómico Hispano Alemán de Calar Alto (CSIC-MPG)

Centro de Astrobiología Depto. Astrofisica (INTA-CSIC)

S. Brittain

Clemson University

A. Carmona

Verimag

D. R. Ciardi

National Aeronautics and Space Administration

W. Danchi

NASA Goddard Space Flight Center

J. Donaldson

University of Maryland

G. Duchene

Verimag

University of California

C. Eiroa

Universidad Autonoma de Madrid (UAM)

D. Fedele

Max Planck-institutet

C. A. Grady

Eureka Scientific, Inc.

I. de Gregorio-Molsalvo

Atacama Large Millimeter-submillimeter Array (ALMA)

C. D. Howard

NASA Ames Research Center

N. Huelamo

Centro de Astrobiología Depto. Astrofisica (INTA-CSIC)

A. Krivov

Friedrich-Schiller-Universität Jena

J. Lebreton

Verimag

René Liseau

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

C. Martin-Zaidi

Verimag

G. Mathews

University of Hawaii at Manoa

G. Meeus

Universidad Autonoma de Madrid (UAM)

I. Mendigutia

Centro de Astrobiología Depto. Astrofisica (INTA-CSIC)

B. Montesinos

Centro de Astrobiología Depto. Astrofisica (INTA-CSIC)

M. Morales-Calderon

Centro de Astrobiología Depto. Astrofisica (INTA-CSIC)

A. Mora

European Space Astronomy Centre (ESA)

H. Nomura

Kyoto University

E. Pantin

Le Commissariat à l’Énergie Atomique et aux Énergies Alternatives (CEA)

I. Pascucci

University of Arizona

N. Phillips

Atacama Large Millimeter-submillimeter Array (ALMA)

C. Pinte

Verimag

L. Podio

Atacama Large Millimeter-submillimeter Array (ALMA)

S. Ramsay

European Southern Observatory (ESO)

B. Riaz

University of Hertfordshire

P. Riviere-Marichalar

Centro de Astrobiología Depto. Astrofisica (INTA-CSIC)

A. Roberge

NASA Goddard Space Flight Center

G. Sandell

NASA Ames Research Center

E. Solano

Centro de Astrobiología Depto. Astrofisica (INTA-CSIC)

I. Tilling

University of Edinburgh

J. M. Torrelles

Universitat de Barcelona

B. Vandenbusche

KU Leuven

S. Vicente

Rijksuniversiteit Groningen

G. J. White

Rutherford Appleton Laboratory

Open University

P. Woitke

University of St Andrews

Publications of the Astronomical Society of the Pacific

0004-6280 (ISSN) 1538-3873 (eISSN)

Vol. 125 927 477-505

Ämneskategorier

Astronomi, astrofysik och kosmologi

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Senast uppdaterat

2018-05-29